AC Voltage and DC Voltage Mixing Protection

This application claims the benefit of U.S. Provisional Application No. 63/665,768, filed Jun. 28, 2024, which is hereby incorporated by reference in its entirety.

The present disclosure generally relates to circuits and methods for protecting against mixing of an AC voltage and a DC voltage.

Current state-of-art battery junction boxes in electric vehicles could potentially allow an inadvertent mixing of AC electrical power from a charging station and DC electrical power from a high-voltage DC battery in the vehicle. For example, the North American Charging System (NACS)-type charging systems combines an AC charging path and a DC charging path prior to entering the vehicle. A failure or a component that does not perform as specified could result in the high-voltage DC battery being exposed to the external AC charging station and vice versa.

Accordingly, those skilled in the art continue with research and development efforts in the field of protecting against mixing of AC voltages and DC voltages.

A protection circuit is provided herein. The system includes an analog-to-digital converter, a control circuit, and a processor. The analog-to-digital converter is operational to generate a sequence of digital values by digitizing a high-voltage signal within a high-voltage area of a vehicle. The vehicle includes a high-voltage battery and a charging socket. The control circuit is operational to control a plurality of contactors coupled to the charging socket in response to a configuration signal. The processor operational to determine if the sequence of digital values represents one of an alternating voltage and a steady-state voltage, assert the configuration signal to command the control circuit to close a pair of DC contactors among the plurality of contactors in response to the sequence of digital values representing the steady-state voltage, and negate the configuration signal to command the control circuit to open the pair of DC contactors in response to the sequence of digital values representing the alternating voltage to prevent a mixture of the alternating voltage and the steady-state voltage in the high-voltage area.

In one or more embodiments, the protection circuit includes a detector circuit operational to monitor the high-voltage signal, assert an enable signal while the high-voltage signal is detected as the steady-state voltage, and negate the enable signal while the high-voltage is detected as the alternating voltage.

In one or more embodiments of the protection circuit, the control circuit is further operational to close the pair of DC contactors in response to the enable signal being asserted and the configuration signal being asserted, and open the pair of DC contactors in response to at least one of the enable signal being negated and the configuration signal being negated.

In one or more embodiments, the protection circuit includes a digital isolator circuit operational to transfer the enable signal from the high-voltage area to the control circuit in a low-voltage area of the vehicle.

In one or more embodiments of the protection circuit, the detector is implemented solely in hardware.

In one or more embodiments, the protection circuit includes a bandpass filter circuit connected between the charging socket and the analog-to-digital converter.

In one or more embodiments, the protection circuit includes a capacitive coupler circuit between the charging socket and the bandpass filter circuit.

In one or more embodiments, the protection circuit includes an isolation circuit operational to transfer the sequence of digital values from the high-voltage area to the processor in a low-voltage area of the vehicle.

In one or more embodiments of the protection circuit, the high-voltage signal is approximately 200 to 1000 volts DC.

In one or more embodiments of the protection circuit, the high-voltage signal is approximately 100 to 260 volts AC.

A method for preventing a mixture of an alternating voltage and a steady-state voltage is provided herein. The method includes generating with an analog-to-digital converter a sequence of digital values by digitizing a high-voltage signal within a high-voltage area of a vehicle. The vehicle includes a high-voltage battery and a charging socket. The method includes controlling with a control circuit a plurality of contactors coupled to the charging socket in response to a configuration signal. Determining with a processor if the sequence of digital values represents one of an alternating voltage and a steady-state voltage, asserting with the processor the configuration signal to command the control circuit to close a pair of DC contactors among the plurality of contactors in response to the sequence of digital values representing the steady-state voltage, and negating with the processor the configuration signal to command the control circuit to open the pair of DC contactors in response to the sequence of digital values representing the alternating voltage to prevent the mixture of the alternating voltage and the steady-state voltage in the high-voltage area.

In one or more embodiments, the method includes monitoring with a detector the high-voltage signal with a detector circuit, asserting an enable signal while the high-voltage signal is detected as the steady-state voltage, and negating the enable signal while the high-voltage is detected as the alternating voltage.

In one or more embodiments, the method includes closing the pair of DC contactors in response to the enable signal being asserted and the configuration signal being asserted, and opening the pair of DC contactors in response to at least one of the enable signal being negated and the configuration signal being negated.

In one or more embodiments, the method includes transferring with a digital isolator the enable signal from the high-voltage area to the control circuit in a low-voltage area of the vehicle.

In one or more embodiments of the method, the monitoring is performed solely in hardware.

In one or more embodiments, the method includes bandpass filtering a signal between the charging socket and the analog-to-digital converter.

In one or more embodiments, the method includes capacitively coupling the charging socket to the bandpass filtering.

In one or more embodiments, the method includes transferring with an isolation circuit the sequence of digital values from the high-voltage area to the processor in a low-voltage area of the vehicle.

In one or more embodiments of the method, the high-voltage signal is approximately 200 to 1000 volts DC, and the high-voltage signal is approximately 100 to 260 volts AC.

A vehicle is provided herein. The vehicle includes a high-voltage area that houses a high-voltage battery, a charging socket accessible from external to the vehicle, an analog-to-digital converter operational to generate a sequence of digital values by digitizing a high-voltage signal within the high-voltage area, a control circuit operational to control a plurality of contactors coupled to the charging socket in response to a configuration signal, and a processor. The processor is operational to determine if the sequence of digital values represents one of an alternating voltage and a steady-state voltage, assert the configuration signal to command the control circuit to close a pair of DC contactors among the plurality of contactors in response to the sequence of digital values representing the steady-state voltage, and negate the configuration signal to command the control circuit to open the pair of DC contactors in response to the sequence of digital values representing the alternating voltage to prevent a mixture of the alternating voltage and the steady-state voltage in the high-voltage area.

The above features and advantages and other features and advantages of the present teachings are readily apparent from the following detailed description of the best modes for carrying out the teachings when taken in connection with the accompanying drawings.

Various embodiments of a protection circuit and/or a method generally prevent a mixing of direct-current (DC) voltage from mixing with an alternating-current (AC) voltage. The DC voltage may be a steady-state voltage within a high-voltage area of an electric vehicle. The DC voltage may be created by an external charging station and/or an internal DC battery pack. The AC voltage may be an alternating voltage generated by a charging station external to the electric vehicle. In various embodiments, the charging station may present the alternating voltage or the steady-state voltage to a charging socket of the electric vehicle, depending on a handshaking protocol exchanged between the charging station and the vehicle at the start of a charging session. The charging socket may be compliant with a North American Charging System (NACS) standard, or similar standards. In the NACS standard, two conductors are used to convey the steady-state voltage, a single-phase alternating voltage, and two lines of a split-phase (2-phase) alternating voltage in different configurations. A protection circuit/method implemented in the vehicle generally detects if the alternating voltage or the steady-state voltage is present in a high-voltage area of the vehicle. If the alternating voltage is detected, DC contactors (e.g., DC Fast Charge contactors) are prevented from closing, or are commanded to open if already closed, thereby avoiding potential damage to the vehicle, the charging station and/or connections in-between. If the steady-state voltage is detected, the DC contactors are closed and, where implemented, link contactors are opened.

1 FIG. 70 70 72 90 72 74 76 90 92 94 96 98 100 Referring to, a schematic diagram illustrating a context of a systemis shown in accordance with one or more exemplary embodiments. The systemgenerally includes a charging stationand a vehicle. The charging stationincludes a charging cableand a charging plug. The vehicleincludes a charging socket, a power converter, a contactor circuit, a battery packand a protection circuit.

78 72 100 74 76 86 92 78 78 Electrical powermay flow between the charging stationand the protection circuitin either direction via the charging cable, the charging plug, charging wires, and the charging socket. In some situations, the electrical powermay be single-phase alternating-current (AC) electrical power. In other situations, the electrical powermay be direct-current (DC) electrical power.

80 76 92 100 80 82 100 82 100 78 78 100 92 92 100 A control signalmay be presented from the charging plug, through the charging socketto the protection circuit. The control signalmay convey one of multiple commandsto protection circuit. The commandsinstruct the protection circuitabout the type of electrical power(e.g., AC or DC) and a direction that the electrical poweris flowing (e.g., into the protection circuitvia the charging socketor out of the charging socketfrom the protection circuit.

84 72 100 74 76 92 84 72 100 78 A communication signalmay be exchanged between the charging stationand the protection circuitvia the charging cable, the charging plug, and the charging socket. The communication signalmay provide standard signaling information between the charging stationand the protection circuitto start, control, and stop the flow of the electrical power.

72 78 90 90 72 72 72 72 The charging stationis operational to provide the electrical power(e.g., electrical current at a voltage) to the vehicleto recharge onboard batteries of the vehicle. In various embodiments, the charging stationsmay be compliant with the North American Charging System (NACS), being standardized as SAE J3400, the SAE International J1772 standard and/or the International Electrotechnical Commission (IEC) 61851-1 standard. The charging stationsmay be a Level 1 AC, a Level 2 AC, a Level 1 DC, a Level 2 DC or an NACS (DC, AC single phase and/or AC split phase) charger. Other charging standards may be implemented to meet the design criteria of a particular application. Some charging stationsmay be placed at fixed locations. Other charging stationsmay be mobile.

76 92 76 92 76 92 78 80 84 72 90 The charging plugimplements an electric charging handle. The charging socketimplements a vehicle charging receptacle. The charging plugis connectable and disconnectable from the charging socket. The charging plugand the charging socketare operational to transfer the electrical power, control signal, and the communication signalbetween the charging stationand the vehicle.

90 90 90 90 90 The vehicleimplements an electric-powered vehicle, a hybrid vehicle, or a plug-in hybrid vehicle. The vehiclesmay implement Level 1 AC, Level 2 AC, Level 1 DC, Level 2 DC or NACS (DC, AC single phase and/or AC split phase) charging capabilities. Other standards may be implemented to meet the design criteria of a particular application. In various embodiments, the vehiclemay include, but is not limited to, a passenger vehicle, a truck, an autonomous vehicle, a motorcycle, a boat, and/or an aircraft. In some embodiments, the vehiclesmay be a stationary object such as a room, a booth and/or a structure. Other types of vehiclesmay be implemented to meet the design criteria of a particular application.

92 98 92 90 92 78 90 92 The charging socketimplements a high-voltage socket through which the battery packis recharged. The charging socketis accessible from external to the vehicle. In various embodiments, the charging socketmay be operational to provide the electrical powerout from the vehicleto external loads. In various embodiments, the charging socketmay be compliant with the North American Charging System, the SAE International J1772 standard and/or the International Electrotechnical Commission (IEC) 61851-1 standard.

94 78 72 96 94 98 98 94 98 94 98 94 90 94 90 94 72 The power converteris operational to accept the single-phase AC electrical power (e.g., electrical power) from the charging stationand present the DC electrical power to the contactor circuit. While operating in a single-phase input mode, the power converteris operational to convert an input single-phase AC electrical power to a first direct-current (DC) electrical power. In various embodiments, the first DC electrical power may be suitable to charge the battery pack. In other embodiments, the first DC electrical power may be converted to a second DC electrical power suitable for charging the battery pack. While operating in a single-phase output mode, the power convertermay receive the second DC electrical power from the battery pack, convert the second DC electrical power to the first DC electrical power, and subsequently convert the first DC electrical power to an output single-phase AC electrical power. In some configurations, the power convertermay receive the first DC electrical power directly from the battery pack, and convert the first DC electrical power to the output single-phase AC electrical power. In various embodiments, the power convertermay be located in the vehicle. In other embodiments, the power convertermay reside at a location independent of the vehicle(e.g., a portable power converteror part of the charging station)

96 96 98 72 96 98 94 96 100 The contactor circuitimplements one or more high-voltage contactors. The contactor circuitis operational to transfer steady-state voltages (e.g., DC power) between the battery packand the charging stations. In various embodiments, the contactor circuitis operational to transfer steady-state voltages between the battery packand the power converter. Control of the contactor circuitis provided by the protection circuit.

98 98 98 72 90 98 98 The battery packimplements as a high-voltage battery or rechargeable energy storage system. The battery packis configured to store electrical energy. The battery packis generally operational to receive electrical power from the charging stationand provide electrical power to other components of the vehicle. The battery packmay include multiple battery modules electrically connected in series and/or in parallel. In various embodiments, the battery packmay provide approximately 200 to 1000 volts DC (direct current) electrical potential. Other battery voltages may be implemented to meet the design criteria of a particular application.

100 90 100 78 72 90 90 The protection circuitimplements a monitoring technique that prevents the mixing of the AC electrical power and the DC electrical power inside the vehicle. The protection circuitmay monitor a charging voltage of the electrical powerreceived from the charging stationin a high voltage area of the vehicle. The monitoring may be accomplished by filtering and digitizing the charging voltage to generate a sequence of digital values. The digital values are presented to a processor in a low-voltage area of the vehicle. The processor determines if the charging voltage is alternating (e.g., an AC charging) or steady-state (e.g., a DC charging).

92 98 98 92 78 If the AC charging is determined, the processor sends one or more commands to a control circuit to (i) open the DC contactors between the charging socketand the battery packand (ii) close link connectors on the output nodes of an AC-to-DC power converter to present DC electrical power to the battery pack. Where implemented, the processor may also send one or more commands to the control circuit to close additional main contactors (not shown) between the charging socketand input nodes of the AC-to-DC power converter to facilitate the conversion of the electrical powerinto a DC voltage.

98 92 98 92 If the DC charging is determined, the processor sends one or more command to the control circuit to (i) open the link contactors between the output nodes of AC-to-DC power converter and the battery packand (ii) close the DC contactors between the charging socketand the battery pack. Where implemented, the processor may also command the control circuit to open the additional main contactors between the charging socketand the input nodes of the AC-to-DC power converter.

2 FIG. 70 70 72 90 illustrates a functional block diagram of an example implementation of the systemin accordance with one or more exemplary embodiments. The systemincludes the charging stationand the vehicle.

72 74 76 110 112 72 110 110 90 72 112 112 90 72 112 The charging stationgenerally includes the charging cable, the charging plug, and one or more power supplies-. In some embodiments, the charging stationmay include a DC Fast Charge (DCFC) power supply. The DCFC power supplyis operational to provide DC electrical power to the vehicleduring a recharging session. In other embodiments, the charging stationmay include an AC power supply. The AC power supplyis operational to provide AC electrical power to the vehicleduring a recharging session. In some embodiments, the charging stationmay include both the DCFC power supply and the AC power supply.

90 92 94 96 98 The vehiclegenerally includes the charging socket, the power converter, the contactor circuit, and the battery pack.

72 78 76 92 90 78 96 98 72 78 76 92 90 78 94 96 98 During a DC charging session, the charging stationprovides steady-state high-voltage electrical powerthrough a pair of wires in the charging plugand the charging socketto the vehicle. The DC electrical poweris routed through the contactor circuit(e.g., one or more “DC” contactors) to the battery pack. During an AC charging session, the charging stationprovides alternating high-voltage electrical powerthrough the charging plugand the charging socketto the vehicle. The AC electrical poweris routed through the power converter, converted to DC electrical power, passed through the contactor circuit(e.g., one or more link contactors) and recharges the battery pack.

3 FIG. 1 FIG. 100 100 100 100 114 90 116 114 92 94 96 98 100 120 122 124 126 114 100 126 128 130 116 a a a a a a illustrates a schematic block diagram of an example implementation of a protection circuitin accordance with one or more exemplary embodiments. The protection circuitmay be a variation of the protection circuit(). The protection circuitmay be spread among a high-voltage areaof the vehicleand a low-voltage areaof the vehicle. The high-voltage areamay include the charging socket, the power converter, the contactor circuitand the battery pack. The protection circuitgenerally includes a capacitive coupler circuit, a bandpass filter circuitan analog-to-digital (A/D) converter circuit, and a high-voltage side of an isolation circuitin the high-voltage area. The protection circuitalso includes a low-voltage side of the isolation circuit, a processorand a control circuitin the low-voltage area.

100 120 122 124 128 126 124 128 a The protection circuitimplements a combined hardware and software path solution. The hardware portion includes two high-resistive nets with DC-decoupling (capacitive) in the capacitive coupler circuitand the bandpass filter circuit. The voltages are read by the A/D converter circuit. The results are transferred to the processorvia isolation circuitand results may be determined using software prior to closing the contactors. For continuous protection, the A/D converter circuitis continuously queried. Diagnostics may also be performed using software executed by the processor.

120 92 122 120 The capacitive coupler circuitis operational to provide a capacitive path from the charging socketto the bandpass filter circuit. The capacitive coupler circuitis operational to block DC voltages and pass AC voltages.

122 122 The bandpass filter circuitis operational to pass AC voltages in a designated frequency band. The designated frequency band is generally from approximately 30 hertz (Hz) to approximately 80 H (e.g., 50 Hz to 60 Hz). The bandpass filter circuitallows AC waveforms to be detected, while suppressing noise and unwanted signals outside that range.

124 122 125 72 78 124 125 92 120 122 72 78 124 125 92 120 122 124 The A/D converter circuitis operational to digitize the filtered signal received from the bandpass filter circuitto create a sequence of digital values. A frequency of the digitization may be several times higher than a frequency of the AC electrical power. Where the charging stationprovides DC electrical power, the A/D converter circuitmay generate a sequence of zero or near-zero digital valuesas the steady-state voltage received at the charging socketis blocked by a combination of the capacitive coupler circuitand the bandpass filter circuit. Where the charging stationprovides AC electrical power, the A/D converter circuitmay generate a sequence of non-zero digital valuesas the alternating voltage received at the charging socketis passed through the capacitive coupler circuitand the bandpass filter circuit. In various embodiments, the A/D converter circuitmay be implemented with an ADBMS2960 converted, available from Analog Devices. Other types of A/D converters may be implemented to meet the design criteria of a particular application.

126 125 114 116 126 126 The isolation circuitis operational to pass the sequence of digital valuesfrom the high-voltage areato the low-voltage area. In various embodiments, the isolation circuitmay be implemented as an LTC6829 isoSPI transceiver, available from Analog Device. In various embodiments, the isolation circuitmay implement opto-coupling, capacitive coupling, and/or inductive coupling. Other isolation circuits may be implemented to meet the design criteria of a particular application.

128 125 116 126 125 114 92 128 The processoris operational to sample the digital valuespresented into the low-voltage areaby the isolation circuit. The sampling is used to determine if the sequence of digital valuesrepresents an alternating voltage or a steady-state voltage in the high-voltage area(e.g., at the charging socketor shortly thereafter). In various embodiments, the processormay be implemented with an Aurix microcontroller unit (MCU), available from Infineon. Other processors may be implemented to meet the design criteria of a particular application.

128 129 130 96 94 98 130 96 78 92 98 a a If a steady-state voltage is detected, the processorasserts a configuration signalto command the control circuitto open one or more link contactors in the contactor circuit, if currently closed, to isolate the power converterfrom the battery pack. The control circuitmay subsequently close one or more DC contactors in the contactor circuitto route the DC electrical powerfrom the charging socketto the battery pack.

128 129 130 92 98 130 96 92 94 94 98 a a If an alternating voltage is detected, the processornegates (e.g., de-asserts) the configuration signalto command the control circuitto the open the one or more DC contactors, if currently closed, to prevent a mixture of the alternating voltage (e.g., at the charging socket) and the steady-state voltage in the high-voltage area (e.g., at the battery pack). The control circuitmay subsequently close one or more link contactors in the contactor circuitto (i) route the AC electrical power from the charging socketto an input of the power converterand (ii) route the DC electrical power from an output of the power converterto the battery pack.

130 96 131 129 128 a The control circuitis operational to control the open/closed condition and open/closed timing sequences of the contactors in the contactor circuitvia control signals. The control and timing may be based on the configuration signalreceived from the processor.

4 FIG. 1 FIG. 3 FIG. 100 100 100 100 100 114 90 116 114 92 94 96 98 100 120 122 124 126 132 134 100 126 128 130 134 116 b b a b b b b illustrates a schematic block diagram of an example implementation of a protection circuitin accordance with one or more exemplary embodiments. The protection circuitmay be a variation of the protection circuit() and/or the protection circuit(). The protection circuitmay be spread among a high-voltage areaof the vehicleand a low-voltage areaof the vehicle. The high-voltage areamay include the charging socket, the power converter, the contactor circuit, the battery pack. The protection circuitgenerally includes the capacitive coupler circuit, the bandpass filter circuit, the analog-to-digital (A/D) converter circuit, the high-voltage side of the isolation circuit, a detector circuit, and a high-voltage side of a digital isolator circuit. The protection circuitalso includes the low-voltage side of the isolation circuit, the processor, a control circuit, and a low-voltage side of the digital isolator circuitin the low-voltage area.

100 120 122 124 128 126 124 128 125 114 b The protection circuitgenerally includes a hardware-only interlock, with a separate hardware/software path for redundancy. The hardware portion includes the two high-resistive nets with DC-decoupling (capacitive) in the capacitive coupler circuitand the bandpass filter circuit. The voltages are read by the A/D converter circuit. The results are transferred to the processorvia isolation circuitand results may be determined using software prior to closing the contactors. For continuous protection, the A/D converter circuitis continuously queried. Diagnostics may also be performed using software executed by the processor(e.g., compare the digital valuesto the interlock results. The second path generally provides a redundant operation to prevent closure of the contactors while alternating voltages are detected in the high-voltage area.

130 130 130 133 133 132 114 130 116 134 133 130 129 133 130 129 b a b b b b 3 FIG. The control circuitmay be a variation of the control circuit(). The control circuitinterlocks the closing of the contactors with an enable signal. The enable signalis generated by the detector circuitand passed from the high-voltage areato the control circuitin the low-voltage areavia the digital isolator circuit. While the enable signalis enabled, the control circuitallows the DC contactors to close per the configuration signal. While the enable signalis disabled, the control circuitholds (e.g., interlocks) the DC contactors open regardless of the configuration signal.

132 122 132 133 132 133 The detector circuitis operational to monitor the high-voltage signal presented by the bandpass filter circuit. If the high-voltage signal is detected as a steady-state voltage, the detector circuitmay assert the enable signalto remove the interlock on the DC contactors. If the high-voltage signal is detected as an alternating signal, the detector circuitmay negate the enable signalto enforce the interlock on the DC contactors.

134 133 114 116 134 The digital isolator circuitis operational to pass the enable signalfrom the high-voltage areato the low-voltage area. In various embodiments, the digital isolator circuitmay implement opto-coupling, capacitive coupling, and/or inductive coupling. Other isolation circuits may be implemented to meet the design criteria of a particular application.

5 FIG. 132 illustrates a schematic diagram of an example implementation of the detector circuitin accordance with one or more exemplary embodiments.

6 FIG. 160 130 a b illustrates a schematic diagram of an example implementation of a contactor driver disable circuitwithin the control circuitin accordance with one or more exemplary embodiments.

160 160 129 133 133 129 162 162 133 133 129 162 162 a a b a b b a b. 6 FIG. The contactor driver disable circuitmay be implemented multiple ways. As illustrated in, a first design of the contactor driver disable circuituses an inverter gate and logic AND gates to enable/disable the configuration signal. While the enable signalis in a logical high state, the inverted enable signalis in a logical low state and the logical AND gates block the configuration signalsand generate off commands to the contactor drives-. While the enable signalis in a logical low state, the inverted enable signalis in a logical high state and the logical AND gates pass through the on/off commands in the configuration signalsto the contactor drives-

7 FIG. 160 130 160 160 b b b a. illustrates a schematic diagram of an example implementation of a contactor driver disable circuitwithin the control circuitin accordance with one or more exemplary embodiments. The contactor driver disable circuitimplements discrete resistors and transistors to provide the same logic as the contactor driver disable circuit

133 1 2 162 162 133 1 2 129 162 162 a b a b. While the enable signalis in a logical high state, the transistors Qand Qare in on states and so generate (pull down) off commands to the contactor drives-. While the enable signalis a logical low state, the transistors Qand Qare in off states and so the on/off commands in the configuration signalsare presented to the contactor drives-

100 The protection circuitgenerally provides a technique of preventing the mixing of DC battery voltage with AC charging voltage in a battery electric vehicle.

The technique involves in the protection circuit use both hardware and software working together to prevent the mixing.

A hardware-only interlock may be included to prevent the mixing.

The detection circuit may use a rectifier circuit to detect AC voltage to determine the enable signal.

The protection circuit may be DC decoupled through capacitors to the high-voltage rails in the high-voltage area of the vehicle.

The technique generally prevents contactors from engaging in the event of a negated enable signal from the detection circuit.

The disabling of the contactors may use logic gates.

The disabling the contactors may use discrete resistors and transistors.

The present disclosure may have various modifications and alternative forms, and some representative embodiments are shown by way of example in the drawings and will be described in detail herein. Novel aspects of this disclosure are not limited to the particular forms illustrated in the above-enumerated drawings. Rather, the disclosure is to cover modifications, equivalents, and combinations falling within the scope of the disclosure as encompassed by the appended claims.

Those having ordinary skill in the art will recognize that terms such as “above,” “below,” “front,” “back,” “upward,” “downward,” “top,” “bottom,” etc., may be used descriptively herein without representing limitations on the scope of the disclosure. Furthermore, the present teachings may be described in terms of functional and/or logical block components and/or various processing steps. Such block components may be comprised of various hardware components, software components executing on hardware, and/or firmware components executing on hardware.

The foregoing detailed description and the drawings are supportive and descriptive of the disclosure, but the scope of the disclosure is defined solely by the claims. As will be appreciated by those of ordinary skill in the art, various alternative designs and embodiments may exist for practicing the disclosure defined in the appended claims.